The present invention primarily addresses the need for preventing unauthorized access to computer disk drives. A minor variation will be described for similar use with video cassette and some audio cassette data storage systems.
As has been itemized in several preceding patents, and eloquently in some (like Canadian Patent No. 1,283,204, Esakoff et al), there are many good reasons for ensuring that such access be limited. These include either software: such as secrets in a competitive business situation; private data of a personal or governmental nature; theft of software programs; inadvertent introduction of computer viruses; or hardware: such as possible damage of the drive by inexperienced users or curious children.